In drip tapes and inline drip irrigation systems used for green house cultivation or outdoor cultivation, it is common that agglutinates by supply of liquefied fertilizers, fur inside tubes, foreign matters, sands, and others stop holes of drip buttons and inline structures. Moreover, after irrigation is finished, there is a difference in height of water contained in the drip tape and the inline drip irrigation system. In this instance, a differential head is generated due to a difference of height of water, and hence, water flows down to a lower region. So, a vacuum state is formed in a drip button labyrinth and an inline structure labyrinth which are located at a higher region, and hence, outside dirty liquid or dust is sucked into a hole of the drip button labyrinth and a hole of the drip line labyrinth, such that the drip tape button hole and the inline drip labyrinth hole are stopped.
Furthermore, in the case of an irrigation system of a mini sprinkler, foreign matters introduced into a pipe stop a nozzle hole of the sprinkler, and hence, they prevent a uniform watering. In order to prevent the above problem, a valve is mounted at an end portion of the pipe, but it also has a problem in that the end portion of the pipe freezes and bursts due to water filling the pipe in winter season.
In order to solve the above problem, an automatic water shut-off valve is mounted at the end portion of the pipe, and the conventional automatic water shut-off valve is used by operating a rubber plate using a spring.
However, the conventional automatic water shut-off valve also has several problems in that it does not work properly due to scale and corrosion by foreign matters and in that it has a limit to vent out lots of fluid. Furthermore, automatic water shut-off valve has another problem in that it is difficult to manage physical properties due to elasticity of the spring.
As another example, FIGS. 1 and 2 illustrate an automatic water shut-off valve 100 for low pressure.
The automatic water shut-off valve 100 includes a main body 102, a fluid supply pipe 101 formed at a lower middle portion of the main body 102, a drain hole 103 formed outside the fluid supply pipe 101, a rubber diaphragm 104 adapted for covering the drain hole 103, and a cap 105 screw-coupled to the main body 102, an edge of the diaphragm 104 being fixed by a pressure fixture 106 pressurized by the cap 105.
The rubber diaphragm 104 includes a hole 104a formed in the middle and connected with the fluid supply pipe 101, a concentrically wave-formed uneven portion 104b, and a ground surface 104c formed around the hole 104a inside the uneven portion 104b in such a way as to get in contact with a ground protrusion 107 projecting from an inner face of the drain hole 103 of the main body 102. Moreover, the pressure fixture 106 includes an arc-shaped ground surface 106a formed on a portion that gets in contact with the rubber diaphragm 104.
The conventional automatic water shut-off valve 100 naturally drains a fluid, which is supplied through the fluid supply pipe 101, through the drain hole 103 in a state where the rubber diaphragm 104 is fixed, but introduces a pressure fluid toward the pressure fixture 106 through the middle hole 104a of the rubber diaphragm 104 connected with a front end of the fluid supply pipe 101 in series when pressure is applied. In this instance, while the wave-formed uneven portion 104b of the rubber diaphragm 104 is unbent as shown in FIG. 2, the ground surface 104c gets in contact with the ground protrusion 107 formed on the main body 102, so that it is prevented that the fluid is discharged out through the drain hole 103.
However, the conventional automatic water shut-off valve 100 has a problem in that foreign matters frequently stay in between the ground surface 104c and the ground protrusion 107, and hence, water leak frequently occurs even though pressure more than the set pressure is applied.